# Basic_Electrical_Wiring

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```					Basic Electrical Wiring

Agricultural Science and
Technology
Electrical Safety
"Shocking Statistics“

 There are approximately 290 accidental electrocutions each year.

 An additional 800 people die in fires caused by faulty electrical
systems every year.

 Thousands are shocked and burned as the result of accidental
contact with electricity every year.

    An estimated \$1.2 billion in property damage occurs each year due
to faulty use of electricity.
Electricity
 Electricity is the flow of electrons in a
conductor.

 The electrons must have a path to and
from its source.

 This path is called a circuit.
Electricity
 Various electrical devices are used as a
part of the circuit.

 These devices are used for a variety of
activities, such as turning the electricity off
and on, providing electricity to various
lights or appliances, etc.
Types of Electrical Currents
 Electrical current comes in two forms:
– Direct current (DC)
Flows in only one direction.
It is usually generated by battery-base electrical
systems and used in the electrical systems of
internal combustion engines or flashlight batteries.
– Alternating current (AC)
Reverses the direction of flow of current many
times each second.
AC is the type used in homes, factories, etc.
Electrical Service
 Service is provided to homes, businesses
and other small users of electricity by
three wires from a utility pole.

 Two of the wires are “hot,” each carrying
120 volts.

 The other wire is “neutral,” and provides
the return path for electricity.
Electrical Service (cont.)
 These wires are connected to a service
entrance, which is where the electricity
enters a building.

 A meter is used in the service entrance to
measure the amount of electricity being
used.
Electrical Service (cont.)
 The service entrance is grounded with a
wire connected to a ground rod driven
several feet into the ground.

 It is needed to provide a return path to the
ground and to carry away stray electrical
current out of the system.
Service Panel
 Follows the meter.

 It houses the circuit
breakers for the
system and is used to
distribute the power to
individual circuits
throughout the
system.
Overcurrent
 When a circuit uses too much electricity, an
overcurrent causes a circuit breaker to trip,
shutting down the power to that circuit.

 The excessive heat caused by an overcurrent
condition may burn or damage a conductor’s
insulation and cause a fire.

 A circuit breaker is a heat-sensitive switch,
which automatically trips when electricity
demand is too great which causes the
temperature in the conductor to get too hot.
Amps Volts Watts
The following relationship exists
between Amps, Volts and Watts.
 Amperes are a measure of the rate of flow
of electricity in a conductor.

 Volts are a measure of electrical pressure.

 Watts are a measure of the amount of
energy or work that can be done by
amperes and volts.
Amps Volts Watts (cont.)

Thus, the following relationship exists.

Work = Pressure x Flow
Or
Watts = Volts x Amperes
Amps Volts Watts (cont.)
 This formula is commonly referred to as
the West Virginia Formula

W=VA

 When we know any two variables of the
formula, we can calculate the other.
Amps Volts Watts (cont.)

Formulas
Watts = Volts x Amps
Volts = Watts / Amps
Amps = Watts / Volts
Calculating Amperage

If we have a 100 watt lamp plugged into a 120 volt
receptacle, we can determine the rate of flow or the
amperes for that circuit.
Amps = 100 Watts / 120 Volts
100 / 120 =.833 Amps
Calculating Watts

If a water heater operates at 20 amps on a 240 volt
circuit, what is the wattage of the appliance?
Watts = 240 Volts x 20 Amps
4800 Watts =240V x 20A
Watts=4800
Calculating Volts
If an electric motor operates at 2880 watts and 12
amps, what would be the voltage requirement for
that motor?
Volts = 2880 Watts / 12 Amps
2880 / 12 = 240 Volts
Identify and draw various symbols
used in drawing wiring diagrams or
schematics.

What symbols are used in drawing various
electrical devices?

In order to successfully draw a wiring circuit
on paper, one needs to use various symbols
that represent the equipment.
Cable Types
Cable Types (cont.)
In cable, there are four different colors or
kinds of wire that one will use depending
on the type of wire that is being used.
Using 12-gauge wire as the example,
there are four types of cable that one may
Cable Types (cont.)

One is 12/2 with ground, which has one
black conductor, one white conductor, and
a bare ground conductor.
Cable Types (cont.)
A second cable is 12/2 without ground,
which is the same as 12/2 with ground
except that no bare ground conductor
exists.
Cable Types (cont.)
A third type of cable is 12/3 with ground,
which has one black conductor, one white
conductor, one red conductor, and one
bare ground conductor.
Cable Types (cont.)
The last type is 12/3 without ground which
is like the 12/2 without ground. It has the
three colored conductors, but no bare
conductor.
The symbols used for conductors
and their respective colors are:
Symbols
Various devices are used as lamp holders,
switches, and receptacles.
Symbols (cont.)
Symbols (cont.)
Symbols (cont.)
to identify terminals and
indicate if wires are spliced or
just crossing over.
Symbols (cont.)
Symbols (cont.)
Diagramming

 Generally, black and red conductors
carry “hot” power or current from the
source to the devices within the
circuit.

 The white conductor is always used to
carry the current back to the source.
Diagramming (cont.)
 When completing the diagram, it may be
helpful to draw the white, neutral
conductor from the source to its final
destination within the circuit, first.

 Duplex receptacles and pull-chain lamp
holders are normally wired so that they
have “hot” or un-switched power at all
times.
Diagramming-3 way switches
 3-way switches are always used in pairs.

 They are needed when one wishes to
control a light from two different locations.
Diagramming-3 way switches
(cont.)
 3-way switches have
three screws or terminals,
one is called control or
common terminal.

 It is often darker colored
than the other two
terminals.

 The other two terminals
are called traveler
terminals.
Diagramming-3 way switches
(cont.)

 When the toggle switch is in one position,
the common terminal carries current to
one traveler terminal.

 When the toggle switch is in the other
position, the common terminal carries
current to the other traveler terminal.
Diagramming-3 way switches
(cont.)

 When diagramming and wiring 3-way switches,
the hot current always enters the control terminal
of one of the switches and always exits out of
the control terminal of the other switch.

 The traveler terminals from one of the switches
must connect to the traveler terminals of the
other switch with no interference.
Diagramming a Single Pole Switch
Circuit
SEP
Breaker

W ire Nut
Circuit
SEP
Breaker

12-2 w/g 

12-2 w/g 
Diagramming a Three Way Switch
Circuit
SEP
Breaker

W
Circuit
SEP
Breaker

B

W
Circuit
SEP
Breaker

12-2 w/g       12-2 w/g 

W

12-3 w/g 
R
Circuit
SEP
Breaker
Circuit
SEP
Breaker

B

W

B
Circuit
SEP
Breaker

12-2 w/g
B

W
12-2 w/g 

B

12-3 w/g 
R

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Description: Electrical wiring instruction document. How to manage Electricity? How to plan a house wiring, safety instructions for Electrical system